Intrinsically safe transducers or transformers are used for the galvanic isolation of circuits in accordance with various standards, wherein energy as well as signals and/or data can be transmitted via the transducers.
Minimum distances for the separation of the circuits and therefore also for the turns or windings of the transformers for different safety classes are specified in various regulations and norms, for example DIN EN 60079-11. These minimum distances depend on the insulating medium, so that the minimum distances are subdivided into solid insulation, clearance and creepage distances. In a typical insulation class, for example protection level 375 V, the minimum separating distance for solid insulation, for example, is 1 mm, the creepage distance in air is 10 mm and the creepage distance under a protective layer is about 3.3 mm.
Intrinsically safe transducers are designed and optimized with regard to the geometry in such a way that the required separating distances for a particular protection level are ensured. This can be provided by wound coils as well as by printed or etched coils on printed circuit boards. Here, in the case of printed or etched coils, it is of advantage that no additional winding processes are required and a good reproducibility can be guaranteed. Further advantages can lie in an improved thermal characteristic for the same core volume. Furthermore, manufacturing costs can be lower.
DE 10 2005 041 131 A1 discloses an intrinsically safe transducer with wound coils, wherein, due to the required insulation distances, the windings of the coils are arranged on different ring cores which are magnetically coupled to one another by means of an additional winding embedded in a printed circuit board. The transducer so formed is based on classical winding technology combined with a printed circuit board technology, wherein the printed circuit board is used for insulation as well as for mechanical fixing.
A transducer, with which the circuits or windings to be insulated are arranged asymmetrically on different printed circuit boards which are subsequently connected on top of one another with a magnetic core to form a transformer or transducer, is proposed in US 2011/0140824 A1. Here, the core can be formed from two halves, which, for example, are glued and/or clamped in order to guarantee mechanical stability.
A planar transducer for miniaturized applications having two windings which lie on opposite sides of an insulating substrate is described in US 2011/0095620 A1. The fundamental physical principle of energy or data transmission is based on induction. Here, however, the transducer is not an intrinsically safe transducer and neither is a magnetic core used.
A transducer or transformer, the conductor tracks of which are manufactured entirely in planar technology with layer structure, in which the conductor tracks are accommodated in a printed circuit board which is joined together to form one piece, is described in EP 0 715 322 A1. The printed circuit board is encompassed by a closed magnetic core.